Roni Ziemba was in the studio last week, dressed head-to-toe in a blue smock, applying paint to one of her Western photographs.

"I focus on the American West," she says cheerfully. "Cowboys and Indians. Horses. My colors are leather, chamois, chaps and saddle."

Long a commercial photographer in Phoenix, Ziemba spent many summers roaming across the Dakotas and Montana, camping out of a van. But last July, she and her husband (she met him through friends in a cowboy bar after she walked across Montana) alighted in Tucson. She finds the art scene here more congenial than up in the Valley of the Sun.

"Art is more part of everyday life here."

To go along with the change of scene, she's changed her photography focus, too, switching from commercial portraits of celebrities and captains of industry to fine art depictions of windswept prairies and cowboys.

"Creatively, I felt stifled," she says.

She's still taking photos with film, but she scans them into the computer, tones them in sepia shades, softens the edges and then prints them out on canvas. "Then I paint around the sides of the images." Sometimes, she'll stain, say, a photo of a horse head or Indian costume with tobacco or grass to give it texture. In "Farmhouse," an austere brown-toned picture of a lonely cabin, she painted ochre into the sky.

Art lovers on this Saturday's Tucson Artists' Open Studios Tour can get a look at "Farmhouse" and other works at the brand-new Collectiv Photographic Arts at 314 E. Sixth St., in the thriving Warehouse District. Run by five partners, including Ziemba, Collectiv is a studio-gallery; each day, visitors can watch one of the five members making art in the studio.

That's what the open studio tour will do on a larger scale, says Dirk Arnold, an artist who is one of the organizers.

"The point of the whole thing is to see artists at work," he says, "and to see the space in which it all happens."

The Collectiv is just one of some 40 studios opening their doors all around Tucson for the tour Saturday, and its five artists are among more than 70 who are participating. Nearly every imaginable medium is represented, with painters, printmakers, ceramicists, jewelry makers, metal workers--and every combination thereof--all participating.

Miles Conrad is the sole encaustic artist on the tour; he'll be doing his wax works at his gallery/studio Conrad Wilde at 210 N. Fourth Ave. Glass artist Tom Philabaum and colleagues will be blowing glass at 711 S. Sixth Ave.

Most of the studios are concentrated downtown, in such familiar venues as the Steinfeld Warehouse, 101 W. Sixth St., where painter Cynthia Miller will display her mixed-media paintings in her studio; the self-styled Mixed Media Painting Group will exhibit in the warehouse's Alamo Gallery.

At the Seventh Avenue Arts District Studios, 549 N. Seventh Ave., in the West University neighborhood, at least 10 artists will be showing their stuff, including painter Dawn Carlson, weaver Crane Day, photographer Kathryn Wilde and Arnold, who's made a name for himself with his small-scale models of Tucson's "endangered architecture."

But a few artists toil on the periphery of the city.

"At first, we were going to keep it downtown, but many of the artists interested were in the outlying areas," Arnold says.

Arnold says he's proud of the number of participants, considering that the artists have organized the tour themselves, on a shoestring budget.

"Typically, the tour gets a little over 100 artists, so this is pretty good."

The tour runs from 11 a.m. to 4 p.m., and art lovers who stick around downtown afterward can attend the Warehouse Arts Festival, put on by the Tucson Arts Coalition. Avant-garde performance artists and family-friendly entertainers alike will put on a free show from 5 to 8 p.m. outside at Stone Avenue and Franklin Street.

The open studio tour itself has metamorphosed through assorted incarnations. For years, the Tucson Arts District Partnership ran the popular program, and when that group virtually dissolved, the Tucson Pima Arts Council picked it up. The arts council staged the last three tours, in fall 2004 and 2005, and in spring 2005, but bowed out this spring. The arts council has recently been embroiled in a power struggle--director Mary Ann Ingenthron resigned and departed as of last Friday--but the council will stage the tour again in the fall.

"We're not funded to do it in the spring," arts council spokeswoman Liz Bustamante says, "but we're definitely going to continue in the fall."

Bustamante joined the organizing committee of artists, and helped out with e-mail addresses, but the only money the tour has this time around is the $20 entrance fee kicked in by each participating artist. In-kind donations have helped. Arnold himself set up a Web site, www.tucsonopenstudios.com, listing all the artists and their locations, and a printer gave the group a deal on paper maps. On the day of the tour, tour-goers can pick up maps at the Seventh Avenue Arts District Studios.

"It sounds crass, but for sales purposes, people who don't have gallery representation rely on it."

Roni Ziemba says she's delighted that she and her co-op partners opened Collectiv in time for the spring tour. She'll be showing her horse images at the Tucson Museum of Art shop this month, in conjunction with the Deborah Butterfield equine sculpture exhibition opening April 22 in the main galleries. Nevertheless, she and other new artists need all the attention they can get. So far, the new studio-gallery is giving the five co-op artists exactly that.

"We have had 250 people come through in the last few weeks," she says, "looking at our work."